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Insights into the stability and substrate specificity of the E. coli aerobic β-oxidation trifunctional enzyme complex

DOI: 10.1016/j.jsb.2020.107494 DOI Help

Authors: Shiv K. Sah-Teli (University of Oulu) , Mikko J. Hynonen (University of Oulu) , Ramita Sulu (University of Oulu) , Subhadra Dalwani (University of Oulu) , Werner Schmitz (Theoder-Boveri-Institut für Biowissenschaften der Universität Würzburg) , Rik. K. Wierenga (University of Oulu) , Rajaram Venkatesan (University of Oulu)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Structural Biology

State: Published (Approved)
Published: March 2020
Diamond Proposal Number(s): 14794

Abstract: Degradation of fatty acids by the β-oxidation pathway results in the formation of acetyl-CoA which enters the TCA cycle for the production of ATP. In E. coli, the last three steps of the β-oxidation are catalyzed by two heterotetrameric α2β2 enzymes namely the aerobic trifunctional enzyme (EcTFE) and the anaerobic TFE (anEcTFE). The α-subunit of TFE has 2E-enoyl-CoA hydratase (ECH) and 3S-hydroxyacyl-CoA dehydrogenase (HAD) activities whereas the β-subunit is a thiolase with 3-ketoacyl-CoA thiolase (KAT) activity. Recently, it has been shown that the two TFEs have complementary substrate specificities allowing for the complete degradation of long chain fatty acyl-CoAs into acetyl-CoA under aerobic conditions. Also, it has been shown that the tetrameric EcTFE and anEcTFE assemblies are similar to the TFEs of Pseudomans fragi and human, respectively. Here the properties of the EcTFE subunits are further characterized. Strikingly, it is observed that when expressed separately, EcTFE-α is a catalytically active monomer whereas EcTFE-β is inactive. However, when mixed together active EcTFE tetramer is reconstituted. The crystal structure of the EcTFE-α chain is also reported, complexed with ATP, bound in its HAD active site. Structural comparisons show that the EcTFE hydratase active site has a relatively small fatty acyl tail binding pocket when compared to other TFEs in good agreement with its preferred specificity for short chain 2E-enoyl-CoA substrates. Furthermore, it is observed that millimolar concentrations of ATP destabilize the EcTFE complex, and this may have implications for the ATP-mediated regulation of β-oxidation in E. coli.

Journal Keywords: Fatty acid β-oxidation; Trifunctional enzyme; TFE; ATP; Substrate channeling; Thiolase; MFE1

Diamond Keywords: Enzymes; Bacteria

Subject Areas: Biology and Bio-materials, Chemistry

Instruments: I04-Macromolecular Crystallography

Other Facilities: PETRA III; EMBL

Added On: 23/03/2020 10:55

Discipline Tags:

Biochemistry Catalysis Chemistry Structural biology Life Sciences & Biotech

Technical Tags:

Diffraction Macromolecular Crystallography (MX)